Hello fellow Guzzisti.
I have recently (and successfully) replaced the main seal of the CARC on my Breva 1100. It would seem that we can expect these seals to start to fail at about 30,000 miles.
Reluctant to spend Â£50+ on the Guzzi part I got mine from Eriks Industrial Services Ltd (www.eriks.co.uk) for ~Â£25. They have service centres all over the UK and are also good for bearings, circlips, etc.
The Guzzi part spec. is 85(I/D) x 110(O/D) x 8(Width) BASL
(BASL specifies the type of seal together with a back-up dust seal)
I found it next to impossible to match the width of 8mm but 10mm is easily available and fits OK.
It is important to get a viton seal in order to handle the temperature range encountered.